182 FXUS65 KTFX 121142 AFDTFX Area Forecast Discussion National Weather Service Great Falls MT 542 AM MDT Wed Apr 12 2017 .DISCUSSION... Today through Friday...Surface analysis this morning shows a broad warm front extending from the WA/OR coast east through SW MT and on through central WY. This front will lift north some this morning, but likely stall across central Montana until later tonight when an approaching shortwave will help kick it north. Warm air advection showers will continue to impact parts of central Montana this morning, but lift will gradually weaken as the front stalls and shower activity should gradually diminish, possibly not even reaching the Hiline. Later tonight, a lee-side low will develop across central Montana and quickly lift NE into southern AB/SK where it will rapidly deepen and close off. This whole process will send a strong cold front through the area Thursday afternoon/evening. Model guidance has trended a bit wetter with this front, likely due to strong upper level dynamics/lift forecast with the associated shortwave. For this reason, I upped QPF a bit THU/THU night, especially along/south of a Great Falls to Lewistown line. Of note, the axis of heaviest precip may need some adjustment in later forecasts. It still looks like it may get unstable enough for a few thunderstorms along and just ahead of the front, mainly east of I- 15. With modest shear associated with the jet moving through, there still exists the potential for a stronger storm or two, mainly from Stanford to Lewistown, but this will likely hinge upon how warm it gets and whether or not the cap can be broken (ie. allowing better instability to be realized). In the wake of the front, a quick shot of colder air will move in with rain showers changing to snow showers, potentially even at lower elevations. Light accumulations are likely at/above pass level across SW MT. At this time, significant impacts from snow are not expected, but this will be monitored in later forecasts. A brief period of stronger wind gusts will likely accompany the front as well. Finally, another shortwave moves through on Friday bringing another chance of showers and maybe a t-storm, especially SW MT. Breezy conditions are likely with this wave as well, especially by Friday afternoon. Martin Friday night through Wednesday...A progressive upper level flow pattern continues across the region this weekend through the first half of next week as several shortwave impulses eject out of persistent troughing off the west coast and lift NE across the Northern Rockies and MT. None of these systems are particularly deep and all move relatively quickly across the region, keeping precipitation amounts relatively light, but the fast movement of these features results in lowering confidence in timing and specific details with time. Breezy and cool conditions are likely Saturday as surface and mid level circulation over southern SK maintains a moderate westerly flow aloft across the region with a weak embedded shortwave disturbance possibly bringing some showers to portions of western and SW MT. The driest day of the period appears to be this Sunday as weak upper level ridging shifts east across the region between shortwave energy moving off to the east and the next incoming shortwave moving onto the west coast. Models are in fair agreement bringing this wave across the area Monday for a period of widespread precipitation with precipitation amounts broadly ranging from one tenth to one third of an inch. Another relatively drier period follows with brief ridging on Tuesday before the next round of energy ejecting out of the Pacific moves in by the middle of next week. Temperatures through much of this period will be near to somewhat below seasonal averages for mid April. Hoenisch && .AVIATION... Updated 1142Z -SHRA along a slow moving/stationary front will continue to impact KGTF/KLWT over the next couple of hours with mtn obscurations and possibly a short period of MVFR CIGS. SHRA should continue to dissipate mid to late morning as lift along the front weakens. Beyond this morning, shower activity should generally be confined to the western mountains, with VFR conditions expected for most terminals. However, an increasing E/SE flow will develop across central Montana later this afternoon/tonight and increasing moisture may lead to lowering CIGs. It is possible that CIGS could fall to MVFR, especially at KCTB/KHVR, but confidence is too low to include MVFR CIGs for now. As the front lifts north tonight, SHRA may begin to increase east of the Rockies late in the period near KCTB. Martin && .HYDROLOGY... Updated 2am Wednesday. Yesterday, visible satellite imagery showed progressive snowmelt occurring at lower elevations across Cascade, Judith Basin, and Fergus counties. The Judith River and its tributaries, including Big Spring Creek and Beaver Creek near Lewistown as well as tributaries of Belt creek, including Otter Creek near Raynesford, appear to be the most likely candidates for high flows from snowmelt. A stream gauge on the Judith River near Winifred indicates the river has risen and is running fast, but there are no reports of impacts at this time. These rivers will continue to monitored closely for additional rises through the end of the week, especially with milder temperatures forecast by Thursday. PN/MARTIN && .PRELIMINARY POINT TEMPS/POPS... GTF 55 40 65 36 / 30 10 50 50 CTB 53 37 58 33 / 20 30 40 10 HLN 59 38 62 34 / 20 10 70 50 BZN 59 36 64 34 / 20 10 50 70 WEY 46 26 49 28 / 20 10 40 70 DLN 55 34 56 31 / 10 10 60 50 HVR 59 39 72 38 / 20 10 20 50 LWT 50 37 68 34 / 30 10 30 50 && .TFX WATCHES/WARNINGS/ADVISORIES... None. && $$ weather.gov/greatfalls